Recently chemistry in the research area of beta-lactam antibiotics has become substantially more complex. Many scientists have directed their efforts to the preparation of novel bicyclic beta-lactam antibiotics differing from naturally occuring penicillins and cephalosporins not only in the nature of the side chain group or the C-3 group in cephalosporins but also in the nature of the ring-hetero atom (i.e. oxygen, nitrogen or even carbon in place of sulfur) and in the positioning of the ring-hetero atom. Of course, in the continuing search for novel beta-lactam antibiotic compounds, researchers have prepared a wide variety of mono and bicyclic beta-lactam containing intermediates. Such intermediates have been prepared either by totally synthetic routes or by molecular modification of penicillins or cephalosporins.
The present invention is directed to novel beta-lactam containing bicyclic intermediates and to a process for their preparation. More particularly the present invention is directed to certain oxazolinoazetidinones of the formula ##STR1## which are useful in the preparation of oxygen analogues of penicillins. The oxazolinoazetidinone intermediates of the present invention are prepared from 2-chloroazetidinones.